1. Field of the Invention
The present invention relates generally to the field of mechanical and architectural drafting and, more specifically, to a drafting apparatus useful in making perspective renderings.
2. Description of the Related Art
Various drafting techniques are used for making perspective renderings by architects and mechanical engineers or designers. One technique involves the use of drafting Mylar overlays that can be purchased in various forms. These overlays are thin sheets 11.times.14 inches or 16.times.20 inches and can be used to transfer alignment dots to a rendering of a structure so as to enable the designer to keep brick lines, board lines, or window lines at a given angle. Unfortunately, this is a slow and difficult process.
A known drafting apparatus for creating perspective renderings is known as the "P-3" or three-point perspective drawing instrument. This instrument is used for drawing small 30.degree. isometric-type renderings, and includes a drawing board having arcuate channels formed in the drawing surface of the board at opposite ends, with each arcuate channel having a different radius. The instrument is small and has some serious limitations. Essentially, it can only provide a 30.degree. isometric perspective and only one horizon line, so that its use is limited to small, non-serious architectural drawings. A T-square slides in and is guided by the grooves, and can be transferred from one groove to the other.
The P-3 instrument is limited in that it only provides a partial arc, and the arcuate grooves are permanently fixed so that only 30.degree. isometric renderings can be created. Moreover, the drawing board itself has to be turned in several different ways to actually achieve multiple uses. For example, if you needed a particular horizon line, you would have to turn the board away from the designer to achieve a horizon line with a wide arc. If the designer desires a different horizon line, the board would have to be turned another way, but in any case, a complete arc is not available and this restricts the horizon line. Also, since the board does not have a wide selection of arcs it does not provide a wide selection of viewpoints.